1. Field of the Invention
This invention relates to a waste toner collection apparatus for collecting waste toner used in an electro-photography type copying machine, a printer or the like adapted to produce a color image by laying toner images of a plurality of different colors one on the other, and an image forming apparatus adapted to be used with such a waste toner collection apparatus.
2. Description of the Background
A cleaning apparatus such as a blade is normally operated to remove the toner remaining on a photosensitive member of an image forming apparatus such as a copying machine or a printer after the end of an image transfer process. The toner removed from the photosensitive member is collected in a waste toner box as waste toner. When the waste toner box becomes full, a sensor detects that the waste toner box is full and the latter is replaced by a new one.
Tandem type image forming apparatus have been marketed in recent years. A plurality of image forming units, each having a photosensitive member, are arranged in parallel in a tandem type image forming apparatus and the toner images of different colors formed on the respective photosensitive members are transferred onto a single sheet of paper and laid one on the other to produce a color image. Each of the photosensitive members occur residual toner in such a tandem type image forming apparatus. When toner images of different colors are transferred one on the other onto an intermediate transfer belt, the intermediate transfer belt also occur residual toner thereon. Apparatus for collecting the residual toners on a plurality of photosensitive members and a transfer medium in a single waste toner box are known. For example, Jpn. Pat. Publication (Kokai) No. 2002-148884 discloses such an apparatus.
The apparatus disclosed in the above-cited Publication is adapted to collapse the waste toner accumulated in the waste toner box and force it to come toward the center space when the waste toner comes above the capacity upper limits at the longitudinal opposite ends of the box main body. Then, as the waste toner that is collapsed and forced to come to the center space gets to the sensing position of a sensor, the sensor detects that the box is full. With the disclosed apparatus, however, waste toner can come above the capacity upper limits at the opposite ends if there is still a space at the center of the box and the sensor does not detect that the box is full. In such a condition, the box can no longer accept waste toner at the opposite ends thereof to consequently lock the waste toner conveyance mechanism at the opposite ends. Additionally, waste toner can spill out from the collection port of the closure member at the opposite ends of the box main body to contaminate the surroundings.
Therefore, there is a demand for waste toner collection apparatus to be used for a tandem type image forming apparatus having a plurality of image forming units arranged that can prevent a particular waste toner conveyance mechanism from being locked or waste toner from spilling out from a particular collection port and also prevent waste toner from being unevenly accumulated in the waste toner box while being able to highly accurately detect the full condition of the waste toner box when collecting the waste toner occurred from the image forming units and/or the transfer medium in a single waste toner box in order to use the waste toner box effectively and collect waste toner in safe. There is also a demand for image forming apparatus that can be used with such a waste toner collection apparatus.